Subtype specificity of alpha-adrenergic receptors in rat heart

Recent studies suggest that two subtypes of alpha-adrenergic receptors (alpha 1 and alpha 2) can be distinguished on the basis of the differential affinities of certain adrenergic ligands for each subtype. We have investigated the binding characteristics of several such ligands for alpha-adrenergic receptors in membrane preparations derived from rat heart. alpha-Adrenergic antagonists competed for binding sites identified by the nonsubtype selective alpha-adrenergic ligand [3H]dihydroergocryptine (DHE) in the order of potency expected for alpha 1-receptors, namely, prazosin (EC50 = 0.35 nM) greater than phentolamine (EC50 = 37 nM) greater than yohimbine (EC50 = 918 nM). Furthermore, the nonsubtype selective radioligand [3H]DHE identified a quantitatively similar number of specific binding sites in rat cardiac membranes as the alpha 1-selective radioligand [3H]prazosin (33 and 36 fmoles/mg protein, respectively), while the alpha 2-selective ligand [3H]clonidine at concentrations up to 20 nM demonstrated negligible specific binding. We conclude that the alpha-adrenergic receptors of rat heart homogenates demonstrate binding characteristics typical of alpha 1-receptors. While we cannot exclude the presence of small numbers of alpha-2 receptors, the similar number of binding sites identified at saturation for the alpha 1-specific ligand [3H]prazosin and for the nonsubtype selective ligand [3H]DHE supports the hypothesis that the alpha-receptors of rat heart are predominantly of the alpha 1-subtype.

Autism and mental retardation: neuropathologic studies performed in four retarded persons with autistic behavior

Four persons who exhibited prominent autistic features throughout life died when 4, 14, 27, and 33 years old. All were mentally retarded. One had documented phenylketonuria, but the cause of mental retardation and autistic behavior was undefined in three. At the time of autopsy, brain weights were within 2 SDs of the norm for age. Complete neuropathologic examination, including analysis of cortical neurons impregnated with the rapid Golgi method, failed to provide clues as to cause or the pathoanatomic substrate of autistic behavior in these cases.

Paroxysmal hypotension associated with sympathetic withdrawal. A new disorder of autonomic vasomotor regulation

We evaluated a patient who had transient episodes of hypotension with clinical and laboratory features apparently distinct from previously recognized disorders of vasomotor regulation. In between his abrupt attacks of hypotension, the patient is asymptomatic and demonstrates normal autonomic modulation of heart rate and blood pressure in response to changes in body position, Valsalva maneuver, cold, and exercise. During periods of hypotension, his plasma norepinephrine falls markedly and he has blunted or absent responses to stimuli that normally have a pressor effect due to sympathetic efferent discharge. Mechanical or known hormonal disorders that produce episodic hypotension have been excluded by extensive testing. We suggest two possible causes for our patient's paroxysmal sympathetic withdrawal: first, a centrally mediated inhibition of sympathetic discharge to peripheral resistance and capacitance vessels, but with no afferent stimulus reflexly producing sympathetic withdrawal readily evident; or second, an episodic release of an unknown endogenous compound with inhibitory effects upon central or preganglionic sympathetic neurons or upon postganglionic sympathetic neurons by a presynaptic inhibition of norepinephrine release.

Relationship between plaques, tangles, and dementia in Down syndrome

In patients with Down syndrome, senile plaques and neurofibrillary tangles accumulate in the cortex at an earlier age than in persons of normal karyotype. We studied 20 Down syndrome patients dying after age 30 (average age, 49); all had neocortical plaques and tangles, but only 3 of 20 had been demented. In 12 cases (average age, 53), tissue was available for quantitative study of plaque and tangle densities and estimation of cell loss in the hippocampus. Although at least 8 of these 12 cases had plaque and tangle densities comparable to those previously reported in demented old people, only 1 had dementia. The regional distribution of plaques and tangles in the hippocampus of these Down cases differed from the pattern in senile dementia. Although Alzheimer-like dementia occurs in Down disease, it is less prevalent than the plethoric plaques and tangles in the cortex.

Physical conditioning augments the fibrinolytic response to venous occlusion in healthy adults

The effects of a 10-week physical-conditioning program on fibrinolytic activity at rest and after stimulation by venous occlusion were studied in 69 healthy adults 25 to 69 years old. Physical conditioning was documented by treadmill performance, and fibrinolysis was measured with a newly developed radioenzymatic assay. Whereas fibrinolysis declined at rest from 16.2 +/- 1.3 to 11.4 +/- 0.8 units (mean +/- S.E.M.) (P = 0.0017), the increment in fibrinolysis produced by venous occlusion was increased from 21.7 +/- 2.9 to 33.8 +/- 4.7 units (P = 0.0037). This augmentation was most marked in women, persons with low initial levels of stimulated fibrinolysis, and persons with low initial physical fitness. We conclude that physical conditioning can enhance the augmentation of fibrinolytic activity that occurs in response to venous occlusion. Enhanced fibrinolysis in response to thrombotic stimuli could be an important mechanism in the beneficial effect of habitual physical activity on the risk of cardiovascular disease.

Effects of exercise on the Type A (coronary prone) behavior pattern

This study presents the initial findings of an attempt to reduce the risk of coronary heart disease (CHD) in a group of health, middle-aged adults by participation in a ten-week, supervised exercise program. Forty-six subjects were classified as Type A or Type B based on their scores on the Jenkins Activity Survey (JAS). Measures of physiologic (blood pressure, serum lipids, body weight, plasminogen activator release, and treadmill performance) and psychologic (scores on the JAS) variables were obtained before and after the exercise program. Subjects were able to successfully reduce the physiologic cardiovascular risk factors. Moreover, Type A subjects lowered their scores on the JAS Type A scale after training, while the scores of the Type B subjected remained unchanged. It is concluded that a supervised program of regular exercise can successfully modify the physiological and psychological variables associated with increased risk for CHD in a nonclinical sample of healthy adults.

Physical conditioning and membrane receptors for cardioregulatory hormones

To seek possible mechanisms for the relative bradycardia induced by physical conditioning we studied the effects of an eight-week swimming programme upon cardiac beta-adrenergic and muscarinic-cholinergic receptors in rats. A training effect was documented by an increase in the ratio of heart wet weight to body weight in the conditioned animals compared with sedentary controls. Cardiac beta-adrenergic receptors as assessed in crude membrane fractions by the binding of (-) (3H) dihydroalprenolol did not differ significantly in either number or affinity in conditioned hearts (30 +/- 2 fmol.mg-1 protein; KD = 1.4 +/- 0.1 nmol.litre-1) compared with sedentary hearts (33 +/- 2 fmol.mg-1; KD = 1.5 +/- 2 nmol.litre-1). Likewise cardiac muscarinic-cholinergic receptors as assessed by the binding of (3H) quinuclidinyl benzilate to crude cardiac membranes did not differ significantly in either number or affinity in conditioned hearts (116 +/- 6 fmol.mg-1 protein; KD = 0.17 +/- 0.03 nmol.litre-1) compared with sedentary hearts (125 +/- 11 fmol.mg-1; KD = 0.19 +/- 0.03 nmol.litre-1). We conclude that the bradycardia of physical training is probably mediated by mechanisms other than alterations in cardiac beta-adrenergic or muscarinic-cholinergic receptors.

Residual areas of acid secretion in the cat stomach after incomplete vagotomy

Proximal gastric vagotomies were carried out in 5 cats and small residual areas of acid secretion (detected by an intragastric pH probe at laparotomy) were recorded and compared 3 and 6 months later. No consistent changes in the size of these residual areas occurred, but further studies using the described technique would be worthwhile.

The syndrome of multiple ankyloses and facial anomalies. A neuropathologic analysis

An infant with the clinical syndrome of multiple joint ankyloses and facial anomalies was examined at autopsy. Neuropathologic analysis disclosed reduced numbers of spinal motor neurons and denervation atrophy of skeletal muscle as the basis for joint ankyloses. A comparison of the neuropathologic findings in this case to those to other clinically similar cases reported recently confirms that the phenotype is not specific, and occurs in a variety of neuro-muscular diseases only some of which are likely to be inherited as an autosomal recessive trait. Diagnostic evaluation of these disorders should include both chromosomal analysis and confirmation of the underlying pathologic process.

Evaluation of an intraoperative test for the completeness of vagotomy

An intraoperative test for the completeness of vagotomy has been evaluated in 103 consecutive operations, including proximal gastric, selective and truncal vagotomies, and truncal vagotomy with antrectomy. At the completion of the vagotomy a pH probe was used to test gastric mucosal response to an intravenous infusion of pentagastrin, aiming to detect undivided vagal fibres by localizing residual areas of acid secretion. Testing was performed in 86 out of 103 vagotomies, and in only 34% was the vagotomy judged complete at the first attempt. Residual areas of acid secretion (usually small) were detected in the remainder, and in early all of these it was possible to abolish these areas by dividing further vagal fibres. It is suggested that intraoperative pH testing improves the likelihood of a complete vagotomy. The test is also useful to plot precisely the antral-body junction when antrectomy is combined with vagotomy.

Familial amentia, unusual ventricular calcifications, and increased cerebrospinal fluid protein

A sibship originally reported by Friedman and Roy as showing severe mental retardation, strabismus, hyperactive tendon reflexes, lalling speech, and foot deformities was restudied. Three major additional findings were noted. The cerebrospinal fluid protein concentration was increased two to three times above normal in four siblings who were available for study. Radiographs of cranial structures in three siblings showed identical pathologic intracranial calcifications which correspond in distribution to the choroid plexus. The choroid plexus was not demonstrable in one patient when radiolabeled 99m-Tc-pertechnetate was injected without perchlorate. Neuropathologic findings in one sibling included small subcortical heterotopias and atrophy of the choroid plexus with encasement by glial fibrils. These findings denote a new heredofamilial neurologic syndrome associated with mental retardation and a disorder of choroid plexus.

Left bundle branch block: angiographic segmental wall motion abnormalities

Ventricular wall motion as studied with contrast ventriculography has been judged normal in the few previously reported cases of patients with left bundle branch block who have neither coronary artery disease nor diffuse cardiomyopathy. However, recent echocardiographic studies have demonstrated a high frequency of segmental asynergy of the septal wall in such patients. In this study left ventricular wall motion was analyzed in 15 patients with left bundle branch block and without significant coronary artery disease or diffuse cardiomyopathy. Biplane cineangiograms from these patients were compared with those from 100 consecutive patients with normal intraventricular conduction and without coronary artery disease or cardiomyopathy using two techniques: qualitative visual inspection and a computer-assisted quantitative method. By qualitative review, 6 of 15 patients with left bundle branch block had regional akinesia or dyskinesia as compared with none of 100 patients with normal intraventricular conduction (chi square = 42.3; P less than 0.001). By quantitative review, 10 of 12 patients with left bundle branch block had abnormal wall motion along at least one hemiaxis. It is concluded that angiographic regional wall motion abnormalities are common in patients with left bundle branch block, even in the absence of coronary artery disease or diffuse cardiomyopathy. The abnormalities may result from the abnormal sequence of ventricular activation rather than from myocardial fibrosis.

Cholesterol metabolism in non-obese women--Failure of physical conditioning to alter levels of high density lipoprotein cholesterol

The effects of a 6-week program of vigorous exercise were studied in 14 non-obese females aged 22--26. Preceding and following a regimen consisting of 30--45 min of jogging 5 days per week, treadmill performance, body weight, total plasma cholesterol, and plasma high density lipoprotein (HDL) cholesterol were assessed. Aerobic performance improved markedly after training as demonstrated by a reduced heart rate at each submaximal treadmill workload, and by an increase in maximal attainable workload. In the absence of a significant change in body weight, total cholesterol fell significantly after training (171 +/- 6 vs 161 +/- 5 mg/dl, P less than 0.05) whereas HDL cholesterol was not significantly altered (63 +/- 5 vs 58 +/- 3 mg/dl). The ratio of total cholesterol to HDL cholesterol fell insignificantly (2.92 +/- 0.19 vs 2.86 +/- 0.14). Our findings differ from prior reports of elevations of high density lipoprotein levels following physical conditioning in men. We suggest that hormonal or other factors leading to higher baseline levels of HDL in women counteract the expected alterations in lipoprotein metabolism induced by physical training.

Clinical and radiologic remission in reticulum cell sarcoma of the brain

Two patients with cerebral reticulum cell sarcoma (CRCS) are reported in whom neurologic abnormalities and radiologic (computerized tomographic [CT] scan) evidence of tumor remitted. In one patient, remission followed craniectomy and corticosteroid therapy and lasted for eight months. In the other patient, at least four remissions occurred over a span of seven years, each in conjunction with the administration of corticosteroids. Corticosteroids may favorably alter the biologic activity of tumor tissue in some cases of CRCS, predisposing to clinical remission and disappearance of tumor on CT scan.

Urinary excretion of dimethyltryptamine in liver disease

The urinary excretion of N,N-dimethyltryptamine (DMT) was higher in patients with severe liver disease than in normal subjects. This difference remained significant when patients with all grades of hepatic encephalopathy were excluded. Patients with liver disease whose mental states were normal excreted amounts of DMT similar to those of patients with a hospital diagnosis of schizophrenia.

The isolated human cortex. A Golgi analysis of Krabbe's disease

The clinical course of a child with Krabbe's leukodystrophy was characterized by clinical seizures, startle myoclonus, and paroxysmal activity recorded by EEG. At autopsy in the fourth year, myelinated subcortical axons were destroyed, virtually completely. Despite isolation from major subcortical and interhemispheric connections, the cell and fiber pattern of the cortex appeared remarkably normal in routine histologic preparations. The normal range of pyramidal and stellate interneurons were also present in rapid Golgi impregnations. The dendritic arbors of pyramidal neurons appeared to be normally formed and were richly invested with spinous postsynaptic specializations. The near-normal morphology of neurons isolated in the neocortex by the myelinoclastic process illustrates the sustaining influence of local intracortical synaptic connections. Alterations of cortical neuronal circuits resulting from synaptic remodeling of local interneuronal connections may account for cortical hyperexcitability as seen in cases of leukodystrophy.

Beta-Adrenergic receptors of human lymphocytes are unaltered by hyperthyroidism

Lymphocytes from 12 patients with untreated hyperthyroidism were compared to lymphocytes from age- and sex-matched euthyroid control subjects to test the hypothesis that alterations in beta-adrenergic response mechanisms occur in human hyperthyroidism. The binding of (-)[3H]dihydroalprenolol, a compound previously shown in these cells to label binding sites having the characteristics of beta-adrenergic receptors, was assayed and no significant difference was found between the two groups. In addition, the accumulation of cAMP in response to isoproterenol was determined by RIA and, again, no difference was found.

Thyroid hormone regulation of alpha-adrenergic receptors: studies in rat myocardium

The effects of alterations in thyroid state on cardiac alpha-adrenergic receptors were investigated by the binding of [3H]dihydroergocryptine (DHE), a potent alpha-adrenergic antagonist. In seven experiments, cardiac membranes from euthyroid rats bound 47 +/- 9 fmoles DHE/mg protein (mean +/- SE) at saturation and demonstrated a dissociation constant (KD) of 2.5 +/- 0.4 nM. Hyperthyroidism, produced by parenteral injection of triiodothyronine, significantly reduced the binding of DHE at all concentrations studied. Scatchard analysis showed this reduction of binding to be due largely to a decreased affinity (KD = 4.0 +/- 0.8 nM, p less than 0.05), although possibly due to a decreased number of binding sites as well (29 +/- 7 fmoles/mg protein, p less than 0.10). Hypothyroidism, produced either by oral propylthiouracil or by surgical thyroidectomy, did not produce a significant change in either the number of binding sites for DHE (56 +/- 8 fmoles/mg protein, p less than 0.40) or in binding affinity (KD = 3.1 +/- 0.5 nM, p less than 0.40). Thus, in addition to the regulation of cardiac beta-receptors by thyroid hormone that has been described previously, thyroid hormone exerts a regulatory effect on the characteristics of cardiac alpha-receptors as well. These changes provide a possible molecular mechanism for the thyroid hormone-induced alterations in cardiac responsiveness to alpha-adrenergic stimulation that have been reported previously.

Alpha-adrenergic receptors in rat myocardium. Identification by binding of [3H]dihydroergocryptine

[3H]Dihydroergocryptine ([3H]DHE) binds to sites in membranes derived from rat myocardium that have the characteristics expected of alpha-adrenergic receptors. The binding is saturable with 41 fmol [3H]DHE bound per mg of protein and of high affinity with KD = 2.9 nM. The binding is rapid and readily reversible. Adrenergic agonists compete with [3H]DHE for binding in the order: epinephrine greater than norepinephrine greater than isoproterenol; and adrenergic antagonists compete for binding in the order: phentolamine greater than propranolol. For comparison, (-)[3H]dihydroalprenolol [(-)[3h]dha] was used to bind to sites in the same membrane preparations having characteristics of beta-receptors. The number and affinity of beta-receptors were quite similar to those of the alpha-receptors with 46 fmol (-)[EH]DHA per mg protein bound at saturation and KD = 2.5 nM. These techniques allowed identification of both beta- and alpha-adrenergic receptors in membranes derived from isolated atria, right ventricular free walls, and left ventricles including interventricular septa. This is the first report documenting direct identification of myocardial alpha-receptors by radioligand-binding techniques and complements the literature previously reporting myocardial inotopic and electrophysiological responses to alpha-adrenergic stimulation.

Ventral porencephaly: a cerebral defect associated with multiple congenital anomalies

An infant with multiple congenital anomalies was found at autopsy to have a porencencephalic defect on the ventral surface of the left frontal lobe. The intracranial defect was seen in association with an anomalous configuration of the circle of Willis. The zone of tissue destruction corresponded to the vascular territory of the anterior choroidal and lenticulo-striate branches of the proximal middle cerebral arteries, which were absent on the left. The developmental anomaly of the circle of Willis may have predisposed to tissue destruction by compromising cerebral perfusion at midgestation, a stage of rapid brain growth.